Thursday, October 30, 2014

High speed re-entry of test platform expected Nov. 1


The lunar north pole and about 60 percent of the Moon's farside is visible in this view captured from 3300 km over the Moon's farside, Oct. 28, from the solar array camera in flight aboard a Chang'e 5 flight dynamic test platform. From Earth, a low Crescent Moon was visible in the evening sky. The phase angles of this image are comparable with those of the Soviet Union's Luna 3 vehicle and its first photographs of the farside captured October 7, 1959. Now well along on the return trip, a challenging re-entry at above 11 km/second, a first for China and the primary reason for the test mission, will occur Nov. 1, according to the State Administration of Science, Technology and Industry for National Defense (SASTIND). Dynamic control and high-speed re-entry technologies are necessary for the success of the scheduled 2017 robotic sample return mission Chang'e 5 [Xinhua].

Comparisons have been made with the incidence angles of this, mankind's first look at the Moon's farside, from the Soviet Union's unmanned Luna 3, October 7, 1959 and the view above of Moon and Earth together from the Chang'e-5 flight dynamics test platform, October 28, 2014. More of the Moon's nearside and less farside was seen in the 1959 facsimile radioed back to Earth, but both views feature prominently Mare Moscoviense and mare-filled Tsiolkovskiy crater and highlight the now-well known differences between the two hemispheres, tidally locked into their permanent relationships with earthbound viewers [MAS/NASA].

Postdoctoral position in lunar magnetism

Data from the Apollo era and Lunar Prospector (1998-1999) is being augmented with more recent data from Kaguya (2007) and especially LADEE (2014) to create a more comprehensive model of the long-established connection between crustal magnetism at the antipodes of the Moon's youngest basins and the anomalously fresh surface materials found at these points, built up into brighter, sometimes beautiful swirl formations. (Animation from lunar crustal thickness maps from GRAIL (2012) by the Science Visualization Studio at the Goddard Space Flight Center [NASA/GSFC].
The Institut de Physique du Globe de Paris (IPGP) is inviting applications for a postdoctoral position in the broad field of lunar magnetism. This one-year position (renewable for a second year) aims to decipher the origin of crustal magnetism by modeling spacecraft-derived magnetic field data.

Potential research projects include modeling the direction of crustal magnetization, comparisons of derived crustal magnetization with measured properties of lunar samples, and correlations between magnetic anomalies and GRAIL gravity. 

As part of a larger project, the applicant will have the opportunity to collaborate with paleomagneticists at CEREGE (Aix en Provence) and geodynamo modelers at ISTerre (Grenoble).

To apply, please provide a CV, publication list, contact information of two references, and a 2-page letter that motivates the applicant's interest in the topic and that describes prior relevant research experience. Please respond by email to Mark Wieczorek (wieczor@ipgp.fr) before March 23, 2015.

Mark Wieczorek
IPGP Planetary and Space Sciences
University of Sorbonne
Paris Cité
email: wieczor@ipgp.fr
Tel: +33 (0)1 57 27 53 08
web: www.ipgp.fr/~wieczor

Wednesday, October 29, 2014

LADEE impact crater found

LADEE impact site on the eastern rim of Sundman V crater, the spacecraft was heading west when it impacted the surface. The image was created by ratioing two images, one taken before the impact and another after the impact. The bright area shows the impact point and the ejecta (things that have changed between the time of the two images). The ejecta form a V shaped pattern extending to the northwest from the impact point. Ratio constructed with LROC images M1163066820RE and M1101816767RE [NASA/GSFC/Arizona State University].
Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera (LROC)
Arizona State University

The Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched from Wallops Island on 6 September 2013 at 11:27 EDT and was visible over much of the eastern coast of the United States. The spacecraft was 2.37 m (7.8 ft) high and 1.85 m (6.1 ft) wide with a mass of 383 kg (844 lb) including the fuel.

After expending most of its fuel during its successful exploration of the Moon the spacecraft had a mass of about only 248 kg (547 lb) when it impacted the surface.

Artist's rendition of the LADEE spacecraft in orbit around the Moon [NASA/JAXA/LP].
Originally LADEE was placed into a retrograde, near-equatorial orbit to study the Moon's surface bound exosphere and dust environment. Since the Apollo era of exploration several conflicting ideas and observations concerning the existence (or not) of near-surface and high altitude dust were debated, and thus one of LADEE’s key science goals was to search for dust particles high above the surface (no dust was found).

LADEE's engines were fired on 11 April 2014 to adjust the orbit in such a way as to guarantee a farside impact if the spacecraft did not survive the 15 April 2014 eclipse. There was a small worry that if the spacecraft failed during the eclipse and was uncontrollable, it might impact near one of the Apollo sites. Over the subsequent 7 days, the low point in LADEE's orbit decreased resulting in an impact on 18 April 2014.

Before and after images of the LADEE impact site [NASA/GSFC/Arizona State University].
As it passed over the western limb as seen from the Earth, the spacecraft impacted the eastern rim of Sundman V crater (11.85°N, 266.75°E). The impact site (11.8494°N, 266.7507°E) is about 780 m from the crater rim with an altitude of about 2590 m, and was only about 295 meters north of its originally predicted location (based on tracking data).

Like the LADEE spacecraft, the impact crater is small, greater than 3 meters in diameter, barely resolvable by the LROC NAC. Based on impact models, a crater of only about 1.8 m (6 ft) diameter is expected. The crater is very small because, as impacts go, LADEE had a low mass and a low density (0.43 g / cm3 vs. larger than 3.0 g / cm3 for an ordinary chondrite meteorite), and was traveling at only a tenth the speed (1699 m/sec - 3800 mph) of an average asteroid.

LADEE impact crater (centered of image) has a distinctive hour-glass albedo pattern indicative of low angle impacts. Bright material extends to the northwest, while only a minor amount was ejected to the southeast; NAC M1163066820RE [NASA/GSFC/Arizona State University].
Because it is so small, the crater is hard to identify among the myriad of small fresh craters that dot the lunar surface. However, as images had been acquired of the impact region before the impact occurred, they could be compared with images acquired after the impact to identify the crater.

Since NAC images are so large (250 megapixels) and the new crater is so small the LROC team coregistered the before and after images (called a temporal pair) and then divided the after image by the before image. In this manner any changes to the surface stick out like a beacon! For the LADEE crater the ejecta forms a triangular pattern primarily downrange (to the west) extending more than 200 meters from the impact site. There is also a small triangular area of ejecta uprange but it extends only about 20-30 meters. The ejecta pattern is oriented WNW consistent with the direction the spacecraft was traveling when it impacted.

Zoomed-in view of the impact site, image is 200 m across, NAC M1163066820RE [NASA/GSFC/Arizona State University].
Explore the catalog of LROC close-ups of lunar spacecraft landing and impact sites, HERE.

Related LADEE Posts:
First Science from LADEE (45th LPSC, March 18 2014)
LADEE's (star tracker) images of the Moon (February 14, 2014)
LADEE economy adds 28 days to mission (February 5, 2014)
LROC captures LADEE from 9,000 meters (January 30, 2014)
Red Moon, Blue Moon Dwayne DayThe Space Review (December 3, 2013)
LADEE begins collecting data (November 22, 2013)
LADEE transitioning out of commissioning phase (November 6, 2013)
Apollo 12 ALSEP first to measure dust accumulation (November 21, 2013)
Chang'e-3 & LADEE: The Role of Serendipity (October 31, 2013)
LADEE LLCD sets new data record (October 25, 2013)
Measuring almost nothing, looking for the almost invisible (October 16, 2013)
LADEE legacies (September 7, 2013)
LADEE Prelaunch Mission Briefing (September 6, 2013)
ESA prepares for LADEE (July 31, 2013)
LADEE arrives at Wallops Island (June 5, 2013)
LADEE ready to baseline dusty lunar exosphere (June 5, 2013)
First laser comm system ready for launch on LADEE (March 16, 2013)
LADEE project manager update (February 6, 2013)
The Mona Lisa test for LADEE communications (January 21, 2013)
Toxicity of lunar dust (July 2, 2012)
Expectations for the LADEE LDEX (March 23, 2012)
The Dust Management Project (August 9, 2010)
LADEE architecture and mission design (July 6, 2010)
DesertRatS testing electrodynamic dust shield (July 5, 2010)
Dust transport and its importance in the origin of lunar swirls (February 21, 2010)
Dust accumulation on Apollo laser reflectors may indicate a surprisingly fast and
more dynamic lunar exosphere
 (February 16, 2010)
NASA applies low cost lessons to LADEE (January 18, 2010)
Nanotech advances in lunar dust mitigation (August 19, 2009)
Moon dust hazard influenced by Sun's elevation (April 17, 2009)
LADEE launch by Orbital from Wallops Island (April 14, 2009)
Understanding the activation and solution properties of lunar dust
for future lunar habitation
 (March 2, 2009)
Respiratory toxicity of lunar highland dust (January 19, 2009)
Toxicological effects of moon dust (June 25, 2008)
Moon dust and duct tape (April 22, 2008)

Friday, October 24, 2014

Bellcomm’s 1968 Lunar Exploration Program

Apollo 15 astronaut James Irwin works beside the mission’s Lunar Roving Vehicle, the first to reach the moon, July 31, 1971. Beginning with Apollo 15, NASA deviated from Bellcomm’s proposed Lunar Exploration Program outlined in 1968 [NASA].
David S. F. Portree
Wired

Bellcomm, Inc., based near NASA Headquarters in Washington, DC, was carved out of Bell Labs in 1962 to provide technical advice to NASA’s Apollo Program Director. The organization rapidly expanded its bailiwick to support nearly all NASA Office of Manned Space Flight advance planning.

In a January 1968 report, Bellcomm planners N. Hinners, D. James, and F. Schmidt proposed a mission series designed to fill a gap which they felt existed in NASA’s lunar exploration schedule between the first piloted Apollo lunar landing and later, more advanced Apollo Applications Program (AAP) lunar flights. The trio declared that their plan was “based upon a reasonable set of assumptions regarding hardware capability and evolution, an increase in scientific endeavor, launch rates, budgetary constraints, operational learning, lead times, and interaction with other space programs,” as well as “the assumption that lunar exploration will be a continuing aspect of human endeavor.”

To bridge the gap between early Apollo and AAP, they envisioned a series of 12 lunar missions in four phases.

Read the full article, HERE.




Thursday, October 23, 2014

China launches lunar sample return test mission

Long March 3C lofts a lunar free-return trajectory and re-entry test module toward cislunar space early Friday morning, October 24, local time. The booster lifted off from Xichang Satellite Launch Center, in China's Sichuan Province, beginning a nine-day mission to 'live fire' test technologies China considers vital to the eventual success of Chang'e-5, a robotic lunar sample return mission now planned for 2017 [Xinhua/Jiang Hongjing].
Test module launch  preparations [CNSA/CLEP].
XICHANG, Sichuan, Oct. 24 (Xinhua) -- China launched an unmanned spacecraft early Friday to test technologies to be used in the Chang'e-5, a future probe that will conduct the country's first moon mission with a return to Earth.

The lunar orbiter was launched atop an advanced Long March-3C rocket from the Xichang Satellite Launch Center in southwest China's Sichuan Province.

The test spacecraft separated from its carrier rocket and entered the expected the orbit shortly after the liftoff, according to the State Administration of Science, Technology and Industry for National Defense.

The whole mission will take about eight days. Developed by China Aerospace Science and Technology Corporation, the spacecraft will fly around the moon for half a circle and return to Earth.

On its return, the test spacecraft will approach the terrestrial atmosphere at a velocity of nearly 11.2 kilometers per second and rebound to slow down before re-entering the atmosphere. It will land in north China's Inner Mongolia Autonomous Region.

The mission is to obtain experimental data and validate re-entry technologies such as guidance, navigation and control, heat shield and trajectory design for a future touch-down on the moon by Chang'e-5, which is expected to be sent to the moon, collect samples and return to Earth in 2017.

It is the first time China has conducted a test involving a half-orbiter around the moon at a height of 380,000 kilometers before having the spacecraft return to Earth.

The test orbiter is a precursor to the last phase of a three-step moon probe project, a lunar sample return mission.

China carried out Chang'e-1 and Chang'e-2 missions in 2007 and 2010, respectively, capping the orbital phase.

The ongoing second phase saw Chang'e-3 with the country's first moon rover Yutu onboard succeed in soft landing on the moon in December 2013. Chang'e-4 is the backup probe of Chang'e-3 and will help pave the way for future probes.

Related Posts:
Geologic characteristics: Chang'E-3 exploration region (January 31, 2014)
ESA on Yutu, as controllers wait for sunrise, February 9 (January 31, 2014)
Problem with solar-powered Yutu rover before nightfall (January 25, 2014)
Chang'e begins long-term science mission (January 18, 2014)
Preliminary Science Results from Chang'e-3 (January 16, 2014)
Chang'e-3 and Yutu survive first lunar night (January 14, 2014)
Chang'e-3 APXS delivers its first surface analysis (January 1, 2014)
Chang'e-3 lander and Yutu rover from LRO (December 31, 2013)
6 of 8 Chang'e-3 science instruments now active (December 18, 2013)
LRO: Finding Chang'e-3 (December 15, 2013)
China's Jade Rabbit, it's time in the Sun (December 15, 2013)
Chang'e-3 Landing Site in Mare Imbrium (December 15, 2013)
Jade Rabbit successfully deployed to the lunar surface (December 14, 2013)
It's not bragging if you do it (December 9, 2013)
"Lunar Aspirations" - Beijing Review (December 9, 2013)
Chang'e-3 safely inserted into lunar orbit (December 6, 2013)
CCTV: Chang'e-3, launch past TLO to Earthview (December 2, 2013)
Chang'e-3 launched from Xichang (December 1, 2013)
Chang'e-3 launch window opens 1 December 1730 UT (November 29, 2013)
Helping China to the MoonESA (November 29, 2013)
Chang'e-3 and LADEE: The Role of Serendipity (October 31, 2013)
Outstanding animation celebrates China's Chang'e-3 (October 29, 2013)
LROC updates image tally of human artifacts on the Moon (September 25, 2013)
Chang'e-3: China's rover mission (May 4, 2013)
China's grand plan for lunar exploration (October 11, 2012)
ILOA to study deep space from Chang'e-3 (September 11, 2012)
China's Long March to the Moon (January 14, 2012)
China plans lunar research base (May 11, 2011)
PRC continues methodical program (March 8, 2011)
Chang'e-2 arrives in mission orbit (October 9, 2010)
Dispatch from Chang'e-2: Sinus Iridum (October 4, 2010)
Chang'e-2 takes direct approach (October 1, 2010)
Chang'e-2 sets stage for future lunar missions (September 3, 2010)
Chang'e-1 research reported published (July 22, 2010)

China to launch sample return re-entry test vehicle

Long March 3C at Xichang [CNSA/CLEP].
Mo Hong'e
Xinhua

China will launch a new lunar mission this week to test technology likely to be used in Chang'e-5, a future lunar probe with the ability to return to Earth.

The experimental spacecraft launched this week is expected to utilize a free-return trajectory to fly high over the Moon's farside and adjust its course for return directly to Earth, according to a source with the State Administration of Science, Technology and Industry for National Defense.

The test module is reportedly in nominal condition and is scheduled to launch sometime prior to local dawn, between Friday and Sunday, from the Xichang Satellite Launch Center.

China's Long March-3C booster will carry the mission through trans-lunar injection.

The mission will involve the spacecraft cislunar navigation, re-entering Earth's atmosphere at above 11 km per second and landing safely on Earth, the source said.

Testing the spacecraft to return land safely at a pre-determined location is considered to be a key capability needed for Chang'e-5, the 2017 mission  designed to land, retrieve lunar samples, launch from the Moon and return the samples to Earth.

Monday, October 13, 2014

LRO: widespread evidence of young lunar volcanism

The feature called Maskelyne is one of many newly discovered young volcanic deposits on the Moon. Called irregular mare patches, these areas are thought to be remnants of small basaltic eruptions that occurred much later than the commonly accepted end of lunar volcanism, 1 to 1.5 billion years ago [NASA/GSFC/Arizona State University].
Dwayne Brown
NASA HQ

NASA’s Lunar Reconnaissance Orbiter (LRO) has provided researchers strong evidence the moon’s volcanic activity slowed gradually instead of stopping abruptly a billion years ago.

Scores of distinctive rock deposits observed by LRO are estimated to be less than 100 million years old. This time period corresponds to Earth’s Cretaceous period, the heyday of dinosaurs. Some areas may be less than 50 million years old. Details of the study are published online in Sunday’s edition of Nature Geoscience.

“This finding is the kind of science that is literally going to make geologists rewrite the textbooks about the moon,” said John Keller, LRO project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The deposits are scattered across the moon’s dark volcanic plains and are characterized by a mixture of smooth, rounded, shallow mounds next to patches of rough, blocky terrain. Because of this combination of textures, the researchers refer to these unusual areas as irregular mare patches.

The features are too small to be seen from Earth, averaging less than a third of a mile (500 meters) across in their largest dimension. One of the largest, a well-studied area called Ina, was imaged from lunar orbit by Apollo 15 astronauts.

Ina appeared to be a one-of-a-kind feature until researchers from Arizona State University in Tempe and Westfälische Wilhelms-Universität Münster in Germany spotted many similar regions in high-resolution images taken by the two Narrow Angle Cameras that are part of the Lunar Reconnaissance Orbiter Camera, or LROC. The team identified a total of 70 irregular mare patches on the near side of the moon.

The large number of these features and their wide distribution strongly suggest that late-stage volcanic activity was not an anomaly but an important part of the moon's geologic history.

The numbers and sizes of the craters within these areas indicate the deposits are relatively recent. Based on a technique that links such crater measurements to the ages of Apollo and Luna samples, three of the irregular mare patches are thought to be less than 100 million years old, and perhaps less than 50 million years old in the case of Ina. The steep slopes leading down from the smooth rock layers to the rough terrain are consistent with the young age estimates.

In contrast, the volcanic plains surrounding these distinctive regions are attributed to volcanic activity that started about 3 1/2 billion years ago and ended roughly 1 billion years ago. At that point, all volcanic activity on the moon was thought to cease.

Several earlier studies suggested that Ina was quite young and might have formed due to localized volcanic activity. However, in the absence of other similar features, Ina was not considered an indication of widespread volcanism.

The findings have major implications for how warm the moon’s interior is thought to be.

An oblique, novel view of the Ina formation (3 km across, 18.65°N, 5.3°E) from the LROC narrow angle camera (resolution 2.5 meters per pixel [NASA/GSFC/Arizona State University].
“The existence and age of the irregular mare patches tell us that the lunar mantle had to remain hot enough to provide magma for the small-volume eruptions that created these unusual young features,” said Sarah Braden, a recent Arizona State University graduate and the lead author of the study.

The new information is hard to reconcile with what currently is thought about the temperature of the interior of the moon.

“These young volcanic features are prime targets for future exploration, both robotic and human,” said Mark Robinson, LROC principal investigator at Arizona State University.

LRO is managed by Goddard for NASA’s Science Mission Directorate at NASA Headquarters in Washington. LROC, a system of three cameras, was designed and built by Malin Space Science Systems and is operated by Arizona State University.

To access the complete collection of LROC images, visit http://lroc.sese.asu.edu/

For more information about LRO, visit http://www.nasa.gov/lro

Some Related Posts:
Hansteen α -   January 15, 2014
Small-scale volcanism on the lunar mare, July 13, 2013
Unassuming volcanic vent north of Aristarchus Plateau, April 1, 2013
New views of the hollows of Rimae Sosigenes, March 28, 2013
Inside Rima Hyginus, June 12, 2012
Ina of the Meniscus Hollows, March 21, 2012
LUNAR MENISCUS HOLLOWS. P. J. Stooke, Department of Geography and Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario, Canada; 43rd Lunar and Planetary Science Conference (2012), #1011.
Whale of a Hollow, March 20, 2012
It's a gas, man, Paul Spudis, Smithsonian Air & Space, October 6, 2011

Thursday, September 25, 2014

Below is a posting for post-doc position at LLNL

The Chemical Sciences Division (CSD) in the Physical and Life Sciences (PLS) Directorate is seeking a planetary sciences postdoctoral researcher. This position requires US citizenship.  

The successful candidate will contribute to several research projects funded by NASA, as well to projects funded by the Department of Energy.  NASA related projects will address the origin and evolution of primordial Solar System condensates, primitive meteorites, lunar samples, and martian meteorites. 

The candidate is expected to have experience with  chemical separation by ion chromatography in a class 100 clean room environment, as with as with isotopic analyses by either multi-collector inductively coupled or thermal ionization mass spectrometry.  This individual will report to the Group Leader for Chemical and Isotopic Signatures.  

Send CV to Lars Borg (borg5@llnl.gov) or Ian Hutcheon (hutcheon1@llnl.gov).

Thursday, May 1, 2014

Elongated crater in west Tranquillitatis

Wall and Rim of Arago E: Full resolution sample from and unusually low-altitude, LROC Narrow Angle Camera (NAC) observation from only 40 km altitude. The sample above shows detail of the northeast wall and floor of Arago E, an excavation of the complex Arago area of western Mare Tranquillitatis. The floor is peppered with boulders that have tumbled down the crater wall. This roughly 800 meter sq. field of view was cropped from LROC NAC M155084711R, LRO orbit 7989, March 18, 2011; resolution 47 cm per pixel, angle of incidence 10° from 40.02 km [NASA/GSFC/Arizona State University].
Raquel Nuno
LROC News System

Arago E (8.5°N ,22.71E°) is an elongated crater located in Mare Tranquillitatis, north of the July 1969 landing site of Apollo 11.

An unusually shaped crater, Arago E is nestled between two wrinkle ridges (see Wide Angle Camera context image below), tectonic features formed by the deformation of the basaltic rocks that make up the lunar maria.

Massive maria lavas placed an extra load on the surface, and these deformations are adjustments of the surface due to the unrelenting force of gravity buckling the rock.

Mosaic from the left and right LROC NAC cameras, LROC NAC observation M155084711R and L, allowing a wider look at the 3.7 km c 6.7 km interior of Arago E. View the original (1000 x 1710) reproduction HERE [NASA/GSFC/Arizona State University].
Elongated Arago E and the ruffled surface of west Tranquillitatis: High angle, early morning illumination highlights the undulations of the Tranquillitatis terrain between 25.5 km Arago, at lower left (6.15°N, 21.43°E) and the elongated, still partially shadowed interior of Arago E at upper center in this roughly 75 km-wide field of view from a mosaic made from two sequential LROC Wide Angle Camera passes, in orbits 6772 and 6773, December 13, 2010. 60 meters per pixel resolution, angle of incidence 74° from 44 km. View the original reproduction (1223 x 1951) HERE [NASA/GSFC/Arizona State University].
This crater's elongated shape is perhaps due to an oblique impact, which impart excess horizontal momentum into the surface leaving an elongated shape. However, for this to happen it's thought a progenitor projectile had to have been arriving from less than 30° above the horizon.

Volcanic vents can also display elongated shapes but don't exhibit raised rims and usually lack a flat floor from pooled impact melt, and both features are seen in Arago E.

Earthview context for Arago E: Arago and Arago E are familiar landmarks in telescopic views from Earth. With only a little practice, even amateurs, using modest telescopes can pick them out and, in their mind's eye at least, also pick out the relatively nearby landing sites of Apollo 11 and Apollo 17, the first and the last Apollo surface expeditions. The full-scale mosaic (inset) was "stacked" from ten frames April 21, 2010 by Yuri Goryachko, Mikhail Abgarian & Konstantin Morozov of Belarus [Astronominsk].
A picture of this crater was taken from orbit during the Apollo 15 mission. (You can see it HERE.) How does the LROC NAC observation, at full resolution HERE, compare?

Related Posts:
A Stark Beauty All Its Own
Constellation Region of Interest at Mare Tranquillitatis
Wrinkle Ridges in Aitken Crater
Wrinkle Ridge vs. Impact Crater
Not Your Average Crater

Tuesday, March 25, 2014

Young Crater Walls (at the Schrödinger Antipode)

Northern rim of an unnamed young crater near 80°N, 278.9°E, north of Catena Sylvester, on the far north nearside and nested within crustal magnetism that may be related to the Moon's youngest impact basin (Schrödinger) on the direct opposite side of the Moon. 1243 meter-wide field of view, sampled from LROC Narrow Angle Camera observation M125130801R, LRO orbit 3574, April 5, 2010; 78.42° incidence, 1.09 meters resolution from 53 km [NASA/GSFC/Arizona State University].].
Hiroyuki Sato
LROC News System

After the unimaginably violent processes of excavation and ejecta emplacement, impact craters gradually change their shapes with time by various processes, such as the isostatic rebound, mass wasting, subsequent impacts, and space weathering.

Today's Featured Image highlights such a post-impact degradation process.

Full-width mosaic of the LROC NAC observation from orbit 3574. The full-sized (4581 x 6319) original can be viewed HERE. Though the high-angle of illumination at this high latitude favors outlines of topography over intrinsic brightness and color,  relatively darker and lighter materials radiate over great distances, aiding studies of how younger materials interact with anomalous local magnetism [NASA/GSFC/Arizona State University].
The lower half of this image (relatively high reflectance) is the crater wall, downslope is to the bottom. The bottom-left dark area is the shadow of southern crater rim. Upper half of the image with a low reflectance surface is the crater rim and the rim slope out of the cavity, mostly covered with impact melt. The low reflectance area at the image center just above the steep wall has multiple horizontal cracks showing where the hardened impact melt has cracked as the steep walls slowly fail and slide into the crater bit-by-bit. These slope failures continuously refresh the crater walls, removing the melt coatings and exposing subsurface materials.

Context image of the unnamed crater and the surrounding area in LROC WAC monochrome mosaic (100 m/pix). Image center is 79.97°N, 278.87°E; image width is about 66 km. The NAC footprint and the location of the opening image are illustrated [NASA/GSFC/Arizona State University].
Most of the fresh craters that we observe have suffered these slides, leaving the commonly observed rootless melt flow features on the rim slopes. Just after the impact occurred, much of the crater interior was covered by impact melt, but these rock veneers are quickly removed from steep slopes leaving fresh outcrops of the target (regolith and, in the case of mare, bedrock).

Arrow marks the young crater highlighted in the LROC Featured Image, released March 25, 2014, west of Poncelet C. The white circle is an approximate reflection of the parameters of the Schrödinger impact basin, the Moon's youngest, centered on a point on the diametrically opposite (antipodal) side of the Moon from the center of Schrödinger, in the far south. Grey lines outline nodes of anomalous crustal magnetism teased from Lunar Prospector (1998-99) data. Noted planetary scientists Lon Hood and Paul Spudis use the excavation caused by the smaller impact to aid in determining how local topography may have been disrupted, as they have suggested, by the force of the Schrödinger basin-forming impact. One challenge will be to determine how much the comparatively weak crustal magnetism interacts with migrating dust and fresh impact debris to create albedo swirl features [NASA/GSFC/Arizona State University]. 
Explore the resurfaced fresh crater walls in full NAC frame yourself, HERE.

Related Posts:
The Moon's antipodal magnetism mystery
Lunar swirl phenomena from LRO
Slope failure near Aratus crater
Sinuous Cracks
Slope Resurfacing
Stratified Ejecta Blocks
Dark Impact Melt Sheet
Thin Dark Layer

Friday, March 21, 2014

Faulted Kipula

This striking mountain within Mare Imbrium was altered at its base by the formation of a lobate scarp. A wrinkle ridge runs into the base of the mountain (bottom right). Image width is approximately 4.5 km. LROC NAC image M1098943917R, spacecraft orbit 14300, August 7, 2012 [NASA/GSFC/Arizona State University].
H. Meyer
LROC News System

This beautiful mountain, called a kipuka, is located in northern Mare Imbrium on the nearside.

Kipukas are the high-standing remnants of a lava-flooded terrain and are quite common on the Moon. In this case, the kipukas are likely part of the inner ring of the Imbrium impact basin that was later flooded by mare basalts. The lobate scarp in the opening image formed due to contraction and the subsequent upward thrusting of the surface.

This scarp looks very familiar, a twin to the famous Lee-Lincoln scarp that the Apollo 17 astronauts explored in the Taurus Littrow Valley.

Wide Angle Camera mosaic showing the field of view of the LROC Featured Image. LROC WMS Image Browser [NASA/GSFC/Arizona State University].
LROC WAC context image of northern Mare Imbrium centered near 49.459°N, 348.136°E. The red box denotes the location of the NAC frame from which the LROC Featured Image released March 21, 2014 was derived. Landmark crater Plato is approximately 101 km across [NASA/GSFC/Arizona State University].
Another common feature in Mare Imbrium are wrinkle ridges like the one above.

Wrinkle ridges form when the surface undergoes compression due to sagging of the lithosphere below large mare deposits. Local tectonic conditions such as the thickness of the mare, direction of stress, and the strength of the basalt affect the final shape of a wrinkle ridge, yielding a variety of ribbon-like ridge forms.

Investigate this complex area for yourself, HERE.

Related Posts:
That's a Relief
Balcony Over Plato
Wrinkled, But How Old?
Wrinkle Ridge in Mare Crisium 
Remnants of the Imbrium impact

Tuesday, March 18, 2014

681 Gigapixel LROC mosaic

Spectacular LROC Northern Polar Mosaic (LNPM) allows exploration from 60°N up to the pole at the astounding pixel scale of 2 meters [NASA/GSFC/Arizona State University].
Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera
Arizona State University

The LROC team assembled 10,581 NAC images, collected over 4 years, into a spectacular northern polar mosaic. The LROC Northern Polar Mosaic (LNPM) is likely one of the world’s largest image mosaics in existence, or at least publicly available on the web, with over 680 gigapixels of valid image data covering a region (2.54 million km2, 0.98 million miles2) slightly larger than the combined area of Alaska (1.72 million km2) and Texas (0.70 million km2) -- at a resolution of 2 meters per pixel! To create the mosaic, each LROC NAC image was map projected on a 30 m/pixel Lunar Orbiter Laser Altimeter (LOLA) derived Digital Terrain Model (DTM) using a software package called the Integrated Software for Imagers and Spectrometers (ISIS).

Figure 1. LNPM superposed on map of the United States.
A polar stereographic projection was used in order to limit mapping distortions when creating the 2-D map. In addition, the LROC team used improved ephemeris provide by the LOLA and GRAIL teams and an improved camera pointing model to enable accurate projection of each image in the mosaic to within 20 meters. Almost exactly 3 years ago the LROC team released a Wide Angle Camera (WAC) mosaic of the same north polar region, the pixel scale was 100 meters.

The new NAC mosaic is 50x higher resolution!

LNPM with three levels of zoom down into Thales crater [NASA/GSFC/Arizona State University].
The LNPM was assembled from individual "collar" mosaics. Each collar mosaic was acquired by imaging the same latitude once every two-hour orbit for a month during which time the rotation of the Moon steadily brought every longitude into view. Each collar mosaic has very similar lighting from start to end and covers 1° to 3° of latitude.

Three collar mosaics illustrating how the images were acquired over time to build the LNPM [NASA/GSFC/Arizona State University].
The Moon does have subtle seasons and the LRO orbit cycles between noon-midnight and terminator orbits (measured as the angle between the spacecraft orbit plane and the sub-solar longitude; known as the beta angle). Lighting at the poles is best during northern summer and when the spacecraft is in noon-midnight orbits (low beta). There are a few gaps in the collar sequences due to spacecraft anomalies and special slewed observations that point the cameras off into space. These gaps were filled with images acquired at other times in the mission. These gap-filling images sometimes have the Sun from the opposite direction of the surrounding collar, resulting in noticeable boundaries.

Two types of orbit that LRO experiences through a six-month cycle. Images acquired during terminator orbits have long shadows from the equator to the pole. For noon-midnight orbits the Sun is overhead (no shadows) at the equator and shadows, though still large, are minimized at the poles.
The LNPM was originally assembled as 841 large tiles due to the sheer volume of data: if the mosaic was processed as a single file it would have been approximately 3.3 terabytes in size! Part of the large size is due to the incredible dynamic range of the NACs. The raw images are recorded as 12-bit data (4096 grey levels) then processed to normalized reflectance (a quantitative measure of the percentage of light reflected from each spot on the ground). To preserve the subtle shading gradations of the raw images during processing the NAC images are stored as 32-bit floating-point values (millions of grey levels). The 32-bit values are four times the disk size of the finalized 8-bit (255 grey levels) representation most computers use to display greyscale images. The conversion process from 32-bit to 8-bit pixels results in saturation (group of pixels all with the maximum value of 255) in the brightest areas.

Printed at 300dpi (a high-quality printing resolution that requires you to peer very closely to distinguish pixels), the LNPM would be larger than a football field.
Even with the conversion, the compressed JPEG images that make up the final product take up almost a terabyte of disk space. To create the zooming and panning Gigapan version, multiple versions of each large tile (32,768 pixels square) were made at varying pixel scales. Next, appropriate labels and grid lines were added for each zoom level in hopes of keeping the user oriented – no sense in getting lost on the Moon! Finally these larger tiles were split into 256-pixel square images, allowing a web browser on an average network to keep up with the amazing detail (only a few tens of kilobytes are needed to see any given location at full resolution). In total the LROC NAC northern polar mosaic required 17,641,035 small tiles to produce the final product.

Dive right in HERE, and explore each of the 681 Gigapixels.

LNPM by the numbers:

Square image: 931,070 pixels across and down
Total pixels: 866,891,344,900  (867 billion)
Pixels with image data: 680,808,991,627 (681 billion)
NAC images: 10,581
Image tiles (256x256): 17,641,035 (18 million)
Mass storage of tiles: 950 Gigabytes

Acknowledgments: The LOLA team provided the high resolution topography used to map project the NAC images and improved spacecraft ephemeris that allowed accurate placement of the images on the lunar latitude longitude grid. Gigapan provided mass storage and a web interface. The United States Geological Survey Astrogeology Science Center provided the ISIS image processing software. The NASA LRO project collected the data and funded the processing effort. The LROC imaging suite was developed and built by Malin Space Science Systems (MSSS).

Thursday, March 13, 2014

Stratification in a Tranquil Sea

Bright talus winds downslope through crags and crannies in the banded scarps exposed in the east wall of Dionysius crater. Horizontal lineations result from differential mass wasting of stratified rock in Mare Tranquillitatis; High (35.12°) incidence Narrow Angle Camera (NAC) mosaic, from both left and right frames, from LROC observation M137434784, orbit 5387, August 26, 2010; east is up in this 450 meter field of view, 49 cm per pixel resolution [NASA/GSFC/Arizona State University].
J. Stopar
LROC News System

Dionysius crater (2.766°N, 17.297°E) is situated on the western edge of Mare Tranquillitatis (the Sea of Tranquility) and excavates both highlands (bright, high reflectance) and mare (dark, low reflectance) materials. Dark banded layers of mare peek out of the eastern wall, where mare material was disturbed by the impact that formed Dionysius crater. Bright talus trails wind downslope through crags and crannies in the dark mare scarps.

Looking closely, the mare appears banded or striated, indicating a non-uniform material. In general, mare are thought to form from large volumes of fluid lavas, much like the Columbia River Basalts in the Pacific Northwest of North America. The stratifications in the lunar mare may represent a series of lava flows in the region.

Blocky overhangs indicate areas more resistant to mass wasting and are interpreted as more coherent basaltic (mare) materials. The thinner, more finely grained layers might represent boundaries between individual lava flows or they may indicate changes in physical properties within a single flow unit. Some of the fine grained layers may even consist of paleoregoliths, ancient regolith surfaces exposed to the vacuum of space in between volcanic eruptions.

LRO Wide Angle Camera (WAC) mosaic of Dionysius and vicinity at local sunrise (featured area, on east wall, remains in deep shadow). Embedded on the southeast 'shore' of Mare Tranquillitatis, the high angle illumination on the surface during this observation opportunity revealed local topography over material brightness, though dark rays, beyond the bright ejecta blanket, can already be seen superpositioned on higher elevations to the west and much lower elevations to the east. 604 nm wavelength view stitched from observations during three sequential orbital passes December 13, 2010; resolution ~60 meters per pixel from 44 km [NASA/GSFC/Arizona State University].
In any case, craters such as Dionysius provide windows into the subsurface structure of the lunar mare. With further study, the total thickness of the mare, as well as the structure and flow mechanics of individual mare flows may be intuited from this and other mare exposures in the walls of impact craters.

Explore the full NAC image, HERE.

Visit these other craters with layered mare exposures:
Lava Flows Exposed in Bessel Crater
Layering in Messier A
Layering in Euler Crater
Layers in Lucian Crater
Marius A
Galilaei's Layered Wall
Dawes
Dionysius Detour

Roughly 150 x 150 km sample of the lunar surface captured from the 1994 Clementine mission. Centered on Dionysius, the data is filtered for Iron Oxide (FeO), a bright constituent of the Mare Tranquillitatis southwest and considered an indication of titanium and a reliable proxy for helium-3, shows how the relatively recent impact that created Dionysius excavated and mixed the sea boundary highlands to the west and ancient basalt plain to the east. Both bright and dark materials radiate more than 100 km from the crater center and beyond the dark ejecta blanket, darker here (though bright in radar and optical data), that dark doughnut is likely a 'false negative' resulting from the spacecraft's low resolution, at this wavelength, of small and fine blocky materials. The bright talus of exposed and very ancient mare basalt layers sifting down the craters walls (particularly on the east) is prominent however, matching the the spectral data of the basin on the east. (Note how older craters, gardened by longer exposure to space weathering, are far more faded into the background [NASA/DOD/USGS].

Tuesday, March 11, 2014

Modified Craters of Moscoviense

Morning light beams over the walls and peaks of an irregularly shaped crater in Mare Moscoviense. This unnamed crater is approximately 17 km in diameter; portion of controlled NAC Mosaic MOSCOVNSLOA, downsampled for web browsing [NASA/GSFC/Arizona State University].
J. Stopar
LROC News System

This crater is one of several similarly shaped craters in Mare Moscoviense. These craters are pockmarked by craggy peaks and fractured floors. The dramatic illumination in the opening image, with the sun low on the horizon, exaggerates the crater's lumpy topography.

This crater, and others like it, represent one type of volcanically modified impact crater. The floor of the crater, shown in detail below, is not much below the surface of the surrounding volcanic plains, and looks nothing like a typical fresh impact crater, such as Giordano Bruno or simple bowl-shaped crater like this one on the farside. Sharp boundaries with flat-lying mare basalts around the crater rim (arrows) indicate where the crater was once surrounded (embayed) and nearly covered by large outpourings of lava. Only the upper part of the crater rim remains.

Unnamed 17km diameter crater in Mare Moscoviense, located at 146.391°E, 26.805°N. Arrows indicate extent of mare embayment. Click on the image for a higher resolution view of the crater floor [NASA/GSFC/Arizona State University].
How did this crater get so lumpy inside? Did volcanic materials push up from beneath the crater floor? Did molten lava intrude through fractures or low points in the crater rim and walls? Did the heat of nearby lava and magma deform the crater like hot plastic? The answer may be a combination of these processes, though most scientists think that the changes in crater shape occur mainly as a result of magma intruding from below.

HDTV still from Japan's lunar orbiter SELENE-1 (Kaguya) show the horizon to horizon extent of Mare Moscoviense, now known to be an unusually thin part of the Moon's crust in the farside lunar highlands. The view is from the north, from an altitude of about 100 km. The wallpaper-sized original can be viewed HERE [JAXA/NHK/SELENE].
Explore this crater and two more like it in entire NAC mosaic, HERE.

Re-visit these other volcanically modified impact craters:

Thursday, March 6, 2014

Squarish Levoisier A of Oceanus Procellarum

Squarish Lavoisier A
The square corner along the north-most rim of Lavoisier A (28.5 km, 36.972°N, 286.74°E), evidence of pre-impact fracturing. LROC NAC observation M112759713L, spacecraft orbit 18324, July 4, 2014; field of view approximately 7 km, resolution 1.41 meters per pixel. LROC Featured Image, released March 6, 2014 [NASA/GSFC/Arizona State University].
Raquel Nuno
LROC News System

Why are most craters circular (even craters found on Earth)? By hurtling objects together at many miles per second in large laboratories, scientists have shown that only the most oblique impacts (less than 10° from the horizon) produce elliptical craters.

The kinetic energy of an impactor behaves much like the energy from a nuclear bomb. The energy is transferred to the target material by a shock wave, and shock waves produced by an impact, whether oblique or head-on, propagate hemispherically. This shape means that energy is being delivered equally in all directions; resulting in a hemispherical void and thus circular craters. However, conditions in nature do not always mirror the laboratory. In fact some craters are nearly square! A portion of the rim of Lavoisier A crater tells a story of the geology before impact. Lavoisier A is a squareish crater with a diameter of 28.5 km in the northwestern portion of Oceanus Procellarum.

Levoisier A from Chang'e-2
High-reflectance, low-angle illumination incidence view of 28.5 km-wide Levoisier A from the Chang'e-2 global mosaic, with real color added from the Clementine survey (1994) [Virtual Moon Atlas 5].
Much of Lavoisier A's shape is thought to be due to preexisting joints or faults in the target rock. These discontinuities create zones of weakness, affecting how the shock wave travels through the material. We find square craters on other planetary bodies such as on the asteroid Eros and here on Earth. An example of a square crater that has been thoroughly studied is Meteor Crater in Arizona.

Levoisier A (Astronominsk)
Among the better views of Levoisier A possible from Earth, situated as it is on the northwest limb of the Moon's nearside, in northwest Oceanus Procellarum, at the direct center of this image from a mosaic by Yuri Goryachko, Mikhail Abgarian and Konstantin Morozov, the Astronominsk team of Minsk, Belarus, sectioned from a full-disk observation photographed September 4, 2012 (below) [Astronominsk].
Levoisier A (Astronominsk)
Levoisier A is marked with an arrow in the full-disk, 4300 by 4900 mosaic of the waning Moon, September 4, 2012 [Astronominsk].
This crater formed on layers of sedimentary rocks that have orthogonal vertical joints running below where the crater formed. The joints disrupted the shock wave flow in certain directions, preventing the formation of a circular crater. Another indication of weaknesses within the target layers is the appearance of the northeastern portion of the crater rim. It appears as if a layer of rock has been peeled back.

Can you find the evidence of pre-impact fracturing (square boundaries) in the full resolution NAC, HERE?

Related Posts:
Squished Crater
Four of a Kind in Catena Davy